In ventilator terminology, which statement is true about the expiratory phase for volume-cycled and pressure-cycled ventilators?

• A. The expiratory phase is active in volume-cycled units.
• B. The expiratory phase is controlled by patient effort.
• C. The expiratory phase is active in pressure-cycled units.
• D. The expiratory phase is passive for both devices.

Answer: (D)

Expiration in ventilators is passive. In both volume-cycled and pressure-cycled units, the inspiratory phase is actively controlled by the machine, but once inspiration ends, air leaves the lungs passively driven by the lungs’ elastic recoil and the expiratory pathway simply opens. The ventilator does not actively push air out during expiration. While patient effort can influence breathing rhythm in some modes, the expiratory flow itself remains passive in both types.